1. Field of the Invention
The disclosure relates to a backlight assembly and a liquid crystal display device using the same. More particularly, the disclosure relates to a backlight assembly and liquid crystal display device using the same in which light generated from a single light source is respectively supplied to two light guiding plates to display two different images, to minimize light loss and to decrease the thickness of elements of the backlight assembly while minimizing the light loss.
2. Description of the Related Art
Generally, liquid crystal is a material in an intermediate state between solid and liquid. As for its electrical property, liquid crystal may change its aligned angle according to an applied electric field. As for its optical property, liquid crystal may change transmissivity thereof according to its aligned angle. The liquid crystal display (LCD) device displays images using these properties of liquid crystal.
A generalized liquid crystal display device has an LCD panel assembly for controlling the liquid crystal and a backlight assembly for supplying light to the LCD panel assembly.
The LCD panel assembly includes an LCD panel and a driving module. The LCD panel precisely controls the aligned angle of the liquid crystal in an area ranging from a few μm2 to a few hundred μm2, and the driving module generates driving signals for driving the LCD panel.
The backlight assembly includes a light source, a light guiding plate, and optical sheets.
As the light source, either cold cathode fluorescent lamp (CCFL) or light emitting diode (LED) is frequently used because of its long life span, easy manufacturability, and low heat generation. The CCFL is mainly used in large-screen LCD devices, whereas LED is mainly used in small-screen LCD devices.
The light guiding plate changes the optical distribution of the light generated from the light source and supplies the redistributed light to the LCD panel. Specifically, the light guiding plate changes a line source of light or a point source of light into a surface source of light.
The optical sheets are installed between the LCD panel assembly and the light guiding plate. The optical sheets make uniform the brightness of the light emitted from the light guiding plate and also control the viewing angle.
In the conventional LCD device having the above construction, images are displayed while light passes through the light guiding plate, optical sheets and the LCD panel assembly sequentially. As a consequence, image can be displayed only in one direction.
Recently, an improved LCD device called “dual liquid crystal display device” is disclosed, and the dual liquid crystal display device can overcome the one directional displaying limitation of the conventional LCD device and can display information in two different directions.
In a conventional dual LCD device, two LCD panels, each performing image display independently, are arranged in an overlapping configuration to display images in two different directions. Specifically, the conventional dual LCD device includes a first LCD device and a second LCD device. The first LCD device includes a first LCD panel, a first light source, a first light guiding plate, first optical sheets, a first light reflective plate and a first receiving container. The second LCD device includes a second LCD panel, a second light source, a second light guiding plate, second optical sheets, a second light reflective plate and a second receiving container.
The first LCD device displays images in a first direction, and the second LCD device display images in a second direction.
The conventional dual LCD device enables displaying images in two different directions, but does so at the expense of other desirable qualities. For example, the extra parts necessary to achieve this dual-display quality increase volume and thickness of the LCD device, making the LCD device bulkier and less desirable.